The pathogenesis of rheumatoid arthritis will be investigated by techniques developed in an animal model. The antigen-induced chronic arthritis in animals results from the sequestration of antigen-antibody complexes in cartilaginous tissues beyond the normal host defense mechanism. Techniques for recovery and identification of tissue-bound immune complexes will be developed in the animal model. Recovery methods will be compatible with maintaining the immunoreactivity of tissue eluates. Identification procedures will separate other components in catilage such as collagen and proteoglycans which are coincidentally removed. Experiments with chemotaxis and lysosomal enzyme release will provide evidence of the inflammatory potential of tissue-bound immune complexes. These assays will also assess the phlogistic ability of other materials in the tissue eluates. The use of the inflammatory assays throughout the duration of the animal arthritis will analyze factors operative early and late in the disease. Causes of the disease in the model will be distinguished from results of chronic inflammation. The methodologies of recovery, identification and assaying for inflammatory potential will be applied to the study of rheumatoid arthritis. Experience with a variety of antigens in the model will help the search for unknown antigens in rheumatoid arthritis. The inflammatory assays will be used to distinguish the causes from the results of the human disease. BIBLIOGRAPHIC REFERENCE: Hollister, J. R. Immunosuppressant Therapy in Juvenile Rheumatoid Arthritis, Arthritis Rheum, 20;(supplement) 545, 1977.